An inner cutter of a reciprocating electric shaver having a plurality of arched shaped cutter blades that are integrally formed on a side edge part of the inner cutter and, while making reciprocating motion, makes sliding contact with an inside surface of an arch shaped outer cutter. Therefore, the signal on the output nodes A or B does not significantly change the voltage at the common node, This is particularly useful when the differential output nodes are connected to differential output buses in a digital-to-analog converter. However, where the stream of bits comprises multiplexed services, it is difficult to measure the phase of the parts of the stream of bits relating to a service of interest without first demapping or demultiplexing the stream of bits.